Elongated working platforms are well known in the art and are commonly used during construction to support workers and equipment at desired elevations. Working platforms of this nature include for example, stationary scaffolding as well as moveable elevating platform assemblies. Although stationary scaffolding is useful, in many instances it is desired to change quickly the elevation of workers and equipment and thus, elevating platform assemblies are advantageous.
One known type of elevating platform assembly is disclosed in U.S. Pat. No. 6,523,647 to Duplessis and assigned to Hydro-Mobile Inc. of L'Assomption, Quebec, Canada assignee of the subject application. This elevating platform assembly comprises an elongated platform that is supported at one end by a mast. A drive mechanism acts between the elongated platform and the mast. The drive mechanism includes a trolley moveable along the mast to which the elongated platform is secured. A motor is mounted on the trolley and drives one or more pinions that cooperate with a rack secured to the mast. In this manner, the elongated platform can be moved upwardly and downwardly along the mast.
The above elevating platform assembly has also been used in a dual mast configuration as shown in FIG. 1. In this environment, an elevating platform 10 spans a pair of laterally spaced masts 12. Each end of the elevating platform 10 is coupled to the drive mechanism on a different one of the masts 12. In order to move the elevating platform 10 upwardly and downwardly along the masts 12, an operator on each mast must control the motor on the trolley that is moveable along that mast so that the drive mechanism 14 remains generally in the same horizontal plane as the drive mechanism on the other mast thereby to ensure that the elevating platform 10 remains level. As will be appreciated, operating the drive mechanisms 14 on the masts 12 separately while maintaining the elevating platform 10 in a level horizontal condition is a difficult task. To permit the drive mechanisms 14 to be vertically spaced, at least to some extent, adaptors 20 acting between each end of the elevating platform 10 and the drive mechanisms 14 on the masts 12 have been employed.
As can be seen in FIG. 1, the connections between the adaptors 20 and the drive mechanisms 14 are such that the portions of the elevating platform that surround the masts 12 remain generally horizontal even though the elevating platform 10 maybe at an angle to the horizontal. Although the movement of the adaptors 20 helps to reduce strain applied to the elevating platform 10 when drive mechanisms 14 deviate from the horizontal, when the angle of the elevating platform 10 deviates from the horizontal by a certain extent one adaptor 20 pulls on the other. This results in point loads identified by arrows 22 generally centered at the adaptors 20 being created and an unwanted horizontal force applied to the masts 12. Also, movement of the adaptors 20 results in movement of the guard rails on the adaptors. As a result, sections of guard rails may overlap or gaps between guard rails may occur causing potential safety concerns. Improvements are therefore desired.
It is therefore an object of the present invention to provide a novel elevating platform assembly suitable for use in single mast and twin mast environments.